A so-called laser ignition system is described in PCT Application WO 2005/066488 A1. This laser ignition system includes an ignition laser which projects into the combustion chamber of an internal combustion engine. The ignition laser is optically pumped from a pumped light source using an optical fiber.
At one end of the ignition laser facing the combustion chamber, a combustion chamber window is present which is transmissive for the laser beams generated in the ignition laser. This combustion chamber window is accommodated in a sealing manner in a housing of the ignition laser. Great demands are placed on the seal between the combustion chamber window and the housing due to the fact that surface temperatures of over 600° C. may occur at the combustion chamber window during operation of the internal combustion engine. In addition, there are intermittent pressure loads of greater than 250 bar. When an ignition laser is used to ignite a gas turbine, although lower pressures prevail in the combustion chamber of the gas turbine, the surface of the combustion chamber window may reach temperatures of up to 1000° C.; in any case, uncontrolled auto-ignition must be prevented.
The interior of the ignition laser should be securely sealed from the extremely high temperatures and pressures. If the exhaust gases should enter the interior of the ignition laser, this would result in failure of the ignition laser.